1. Field of the Invention
The present invention relates to a polyvinyl chloride composition containing aluminum powders which affords by molding a weather-resisting resinous molded article of metallic luster in appearance. More particularly, the present invention relates to a moldable polyvinyl chloride composition containing platelet aluminum powders of a specific size in a specific proportion which affords by molding a weather-resisting molded article of metallic luster in appearance.
2. Related Art Statement
From the past, a surface treatment such as plating, vapor deposition, sputtering or painting is put into practice as a means for imparting metallic luster to molded articles made of resinous materials such as polyvinyl chloride, ABS resin and acrylic resin. Typical methods recently developed as such surface treatment are disclosed, for example, in U.S. Pat. Nos. 4,104,432, 4,214,016, 4,369,225 and 4,442,167. According to these prior arts, a molded resinous article is generally overlaid successively with a base coat, a thin metallic film and a protective top coat. In this case, the thin metallic film is applied onto the surface of the base coat by vapor deposition or sputtering.
Besides these surface treatments, incorporation of a powdery metal into resinous materials followed by molding of the resinous materials, for example, by extrusion is also put into practice as another means for imparting metallic luster to molded articles.
Among these means for furnishing resinous articles with metallic feeling and appearance, the firstly mentioned surface treatment of a resinous article by sputtering, ion plating or the like means provides a lustrously metallized resinous product with an excellent metallic appearance and durability and is thus recommended as the most preferable means at present. However, such surface treatment requires a series of complicate steps, especially a tremendous metallizing step for molded resinous articles in a complicate shape, so that the cost for manufacturing the products becomes higher. Because of affording a high quality metallized products, such metallizing treatment is commercially attractive for manufacturing relatively expensive goods but is not economical for manufacturing low cost products of general use.
On the other hand, the latter mentioned method comprising incorporation of metal powders into a moldable resinous material is econmically advantageous since a molded resinous product with metallic appearance can be obtained simply by molding the material, for example, by injection molding, extrusion, calendering or blow molding. As the metal powders have homogeneously been dispersed in the resinous material, there is no fear of delamination of a metal film unlike the case of the metallization of molded articles. For these reasons, this method is now widely utilized for manufacturing toys and low cost daily necessaries where severe resisting properties are not required. From the economical point of view, metal powders to be incorporated into a moldable resinous material are aluminum powders.
In case of various outdoor parts used for motor vehicles and houses, which are exposed under severe weathering action for a long period of time, the products with metallic appearance obtained by the latter mentioned method are found inferior in weather-resisting property. Among various resinous materials, polyvinyl chloride for which a soft type resin or a hard type resin is commercially available is widely employed for exterior parts of motor vehicles and houses because of its good weather-resisting property and low cost. In case of polyvinyl chloride, too, however, its weather-resisting property is significantly deteriorated when this resin is incorporated with aluminum powders. A polyvinyl chloride composition having been incorporated with aluminum powders forms black spots or tends to lose its lustrously metallic appearance during its use as exterior resinous goods by the influence of ultraviolet rays or rain. Thus, even polyvinyl chloride is unsuited as a resinous material containing aluminum powders from which exterior parts are manufactured.
Hence, there is a great demand for developing a moldable polyvinyl chloride composition having been incorporated with aluminum powders which can easily be molded to afford a molded polyvinyl chloride article having lustrously metallic appearance with noble feeling and having excellent resistance to weathering action.